/* eslint-disable */
/**
 * Created by SLICE_30_K on 2017/5/22.
 *
 * 支持一般Base64的编码和解码
 * 支持符合RFC_4648标准中"URL and Filename Safe Alphabet"的URL安全Base64编解码
 * 支持中文字符的编解码(Unicode编码)
 */
;(function (root, factory) {
  if (typeof exports === 'object') {
    // CommonJS
    module.exports = exports = factory()
  } else if (typeof define === 'function' && define.amd) {
    // AMD
    define(factory)
  } else {
    // Global (browser)
    window.BASE64 = factory()
  }
}(this, function () {
  var BASE64_MAPPING = [
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3',
    '4', '5', '6', '7', '8', '9', '+', '/'
  ]
  var URLSAFE_BASE64_MAPPING = [
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '0', '1', '2', '3',
    '4', '5', '6', '7', '8', '9', '-', '_'
  ]

  var _toBinary = function (ascii) {
    var binary = []
    while (ascii > 0) {
      var b = ascii % 2
      ascii = Math.floor(ascii / 2)
      binary.push(b)
    }
    binary.reverse()
    return binary
  }

  var _toDecimal = function (binary) {
    var dec = 0
    var p = 0
    for (var i = binary.length - 1; i >= 0; --i) {
      var b = binary[i]
      if (b == 1) {
        dec += Math.pow(2, p)
      }
      ++p
    }
    return dec
  }

  var _toUTF8Binary = function (c, binaryArray) {
    var mustLen = (8 - (c + 1)) + ((c - 1) * 6)
    var fatLen = binaryArray.length
    var diff = mustLen - fatLen
    while (--diff >= 0) {
      binaryArray.unshift(0)
    }
    var binary = []
    var _c = c
    while (--_c >= 0) {
      binary.push(1)
    }
    binary.push(0)
    var i = 0, len = 8 - (c + 1)
    for (; i < len; ++i) {
      binary.push(binaryArray[i])
    }

    for (var j = 0; j < c - 1; ++j) {
      binary.push(1)
      binary.push(0)
      var sum = 6
      while (--sum >= 0) {
        binary.push(binaryArray[i++])
      }
    }
    return binary
  }

  var _toBinaryArray = function (str) {
    var binaryArray = []
    for (var i = 0, len = str.length; i < len; ++i) {
      var unicode = str.charCodeAt(i)
      var _tmpBinary = _toBinary(unicode)
      if (unicode < 0x80) {
        var _tmpdiff = 8 - _tmpBinary.length
        while (--_tmpdiff >= 0) {
          _tmpBinary.unshift(0)
        }
        binaryArray = binaryArray.concat(_tmpBinary)
      } else if (unicode >= 0x80 && unicode <= 0x7FF) {
        binaryArray = binaryArray.concat(_toUTF8Binary(2, _tmpBinary))
      } else if (unicode >= 0x800 && unicode <= 0xFFFF) { // UTF-8 3byte
        binaryArray = binaryArray.concat(_toUTF8Binary(3, _tmpBinary))
      } else if (unicode >= 0x10000 && unicode <= 0x1FFFFF) { // UTF-8 4byte
        binaryArray = binaryArray.concat(_toUTF8Binary(4, _tmpBinary))
      } else if (unicode >= 0x200000 && unicode <= 0x3FFFFFF) { // UTF-8 5byte
        binaryArray = binaryArray.concat(_toUTF8Binary(5, _tmpBinary))
      } else if (unicode >= 4000000 && unicode <= 0x7FFFFFFF) { // UTF-8 6byte
        binaryArray = binaryArray.concat(_toUTF8Binary(6, _tmpBinary))
      }
    }
    return binaryArray
  }

  var _toUnicodeStr = function (binaryArray) {
    var unicode
    var unicodeBinary = []
    var str = ''
    for (var i = 0, len = binaryArray.length; i < len;) {
      if (binaryArray[i] == 0) {
        unicode = _toDecimal(binaryArray.slice(i, i + 8))
        str += String.fromCharCode(unicode)
        i += 8
      } else {
        var sum = 0
        while (i < len) {
          if (binaryArray[i] == 1) {
            ++sum
          } else {
            break
          }
          ++i
        }
        unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 1, i + 8 - sum))
        i += 8 - sum
        while (sum > 1) {
          unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 2, i + 8))
          i += 8
          --sum
        }
        unicode = _toDecimal(unicodeBinary)
        str += String.fromCharCode(unicode)
        unicodeBinary = []
      }
    }
    return str
  }

  var _encode = function (str, url_safe) {
    var base64_Index = []
    var binaryArray = _toBinaryArray(str)
    var dictionary = url_safe ? URLSAFE_BASE64_MAPPING : BASE64_MAPPING

    var extra_Zero_Count = 0
    for (var i = 0, len = binaryArray.length; i < len; i += 6) {
      var diff = (i + 6) - len
      if (diff == 2) {
        extra_Zero_Count = 2
      } else if (diff == 4) {
        extra_Zero_Count = 4
      }
      var _tmpExtra_Zero_Count = extra_Zero_Count
      while (--_tmpExtra_Zero_Count >= 0) {
        binaryArray.push(0)
      }
      base64_Index.push(_toDecimal(binaryArray.slice(i, i + 6)))
    }

    var base64 = ''
    for (var i = 0, len = base64_Index.length; i < len; ++i) {
      base64 += dictionary[base64_Index[i]]
    }

    for (var i = 0, len = extra_Zero_Count / 2; i < len; ++i) {
      base64 += '='
    }
    return base64
  }

  var _decode = function (_base64Str, url_safe) {
    var _len = _base64Str.length
    var extra_Zero_Count = 0
    var dictionary = url_safe ? URLSAFE_BASE64_MAPPING : BASE64_MAPPING

    if (_base64Str.charAt(_len - 1) == '=') {
      if (_base64Str.charAt(_len - 2) == '=') { // 两个等号说明补了4个0
        extra_Zero_Count = 4
        _base64Str = _base64Str.substring(0, _len - 2)
      } else { // 一个等号说明补了2个0
        extra_Zero_Count = 2
        _base64Str = _base64Str.substring(0, _len - 1)
      }
    }

    var binaryArray = []
    for (var i = 0, len = _base64Str.length; i < len; ++i) {
      var c = _base64Str.charAt(i)
      for (var j = 0, size = dictionary.length; j < size; ++j) {
        if (c == dictionary[j]) {
          var _tmp = _toBinary(j)
          /* 不足6位的补0 */
          var _tmpLen = _tmp.length
          if (6 - _tmpLen > 0) {
            for (var k = 6 - _tmpLen; k > 0; --k) {
              _tmp.unshift(0)
            }
          }
          binaryArray = binaryArray.concat(_tmp)
          break
        }
      }
    }
    if (extra_Zero_Count > 0) {
      binaryArray = binaryArray.slice(0, binaryArray.length - extra_Zero_Count)
    }
    var str = _toUnicodeStr(binaryArray)
    return str
  }

  var __BASE64 = {
    encode: function (str) {
      return _encode(str, false)
    },
    decode: function (base64Str) {
      return _decode(base64Str, false)
    },
    urlsafe_encode: function (str) {
      return _encode(str, true)
    },
    urlsafe_decode: function (base64Str) {
      return _decode(base64Str, true)
    }
  }

  return __BASE64
}))
